Petersburg, Ky. -- Is creationism a valid model for explaining the origins of the Earth? That was the central question debated Tuesday by Bill Nye, known as "the Science Guy" by a generation of Americans, and Ken Ham, founder of a group that promotes the view that God created the universe 6,000 years ago and that the Bible factually tells that story.

The 2 1/2 hour debate took place at the Creation Museum, which Ham heads, in a setting the NBC News said "had the air of a presidential debate."

Moderated by CNN's Tom Foreman, the contestants presented barrages of slides and videos as they made their points to a live audience of 800 people. YouTube streaming video brought the proceeding to up to 532,000 simultaneous viewers.

Creationism not only is a viable option for explaining the origins of the universe, it is the only option, Ham said.

Colin Daileda, writing on Mashable, said Ham drew a distinction between "observational science," the kind that can be tested by experiment, and "historical science," which he said interprets the past through existing evidence.

"Creation is the only viable model of historical science confirmed by observational science in today's modern scientific era," Ham said.

Ham returned to that theme throughout the debate, saying in essence that if you weren't there you can't prove it, Daileda said.

The Bible's account of the creation of the universe over six days works just as well as the evolutionary model, Ham said. Radioisotope tests that show the world far older than 6,000 years are fallible, he said.

"I find there's only one infallible dating method," Ham said, according to NBC. "It's a witness who was there, who knows everything and told us, and that's from the word of God."

Nye, executive director of The Planetary Society, said he and the rest of the scientific community hold that the universe was created in a big bang and that life evolved over billions of years, the Associated Press said.

"I just want to remind us all there are billions of people in the world who are deeply religious, who get enriched by the wonderful sense of community by their religion," Nye said. "But these same people do not embrace the extraordinary view that the Earth is somehow only 6,000 years old."

Nye pointed to seasonal changes shown in Antarctic ice cores going back 680,000 years and tree-ring records stretching back 9,800 years. If the world was only 6,000 years old, he said, the seasonal swings shown in the ice and the trees would have been far more rapid -- and something people would have noticed.

He rejected Ham's distinction between "observational" and "historical" science, saying the notion that natural laws have changed over time was at the heart of their disagreement.

Nye also wanted evidence that the Bible theories could be used to explain different elements of the world, Daileda said. Ham's model, Nye said, cannot make predictions and show results.

The outcome of the debate betweeen evolution and creation is key to the nation's future as a scientific leader, Nye said.

Ham responded by playing clips of several scientists, including MRI scanner inventor Ray Damadian, who said they had reconciled a literal acceptance of the Biblical creation with their work in science.

Who won? Both sides were represented on Twitter.

#creationdebate there shouldn't be debate. Evolution is fact proven by science. I understand why people have "faith" but don't understand.